8-exo-formyl-2,6-exo-tricyclo(5.2.1.02,6)decane, method of preparing it and use of the same

ABSTRACT

It was found that 8-exo-formyl-2,6-exo-tricyclo[5.2.1.0 2 ,6 ]decane having the constitution and stereochemistry of formula (I) possesses particularly useful olfactory properties which are clearly superior to those of the 8-endo-epimer and which already have an effect if compound (I) is enriched with mixtures of 8-exo- and 8-endo-epimers. Compound (I) can therefore be advantageously used, in pure or enriched form, as a scent or as a component of perfume compositions. To prepare an enriched epimer mixture, a mixture obtained in a known manner (U.S. Pat. No. 3,270,061) and having an exo/endo ratio of 1.45:1 is brought into equilibrium by base catalysis, preferably by the action of alkali hydroxides in alcoholic solution, to give an exo/endo ratio of 5.25:1. Alternatively, the enriched epimer mixture can be prepared starting from 8-formyl-2,6-exo-tricyclo[5.2.1.0 2 ,6 ]decene-3(4), catalytically hydrogenated for example with palladium coal and then optionally brought into equilibrium. Or 2,6-exo-tricyclo[5.2.1.0 2 ,6 ]decene-8 can be hydroformylated and also optionally brought into equilibrium. The pure compound (I) is prepared by reducing preferably a mixture of 8-exo- and 8-endo-epimers obtained in the manner known per se to a mixture of the corresponding alcohols, from which the 8-exo-configured methylol is isolated by chromatography or distillation and oxidized to obtain the aldehyde (compound I) again.

This appln. is a PCT of 371 of DE92/00,307 filed Apr. 10, 1992, pending.

In modern industrial perfumery there ms a permanent demand for new scentproducts having, in addition to high stability and hence variedtechnical possible applications, scent notes that are as original andaesthetic as possible. An additional factor in the industrial productionof scents is the provision of such new scents which, starting fromsynthetic raw materials, are available in large quantities and cheaply.

The present invention relates to8-exo-formyl-2,6-exo-tricyclo[5.2.1.0²,6 ]decane (1) which is a valuablenew scent either in its pure form or in an enriched form together withits 8-endo-isomer 2. ##STR1##

It is novel that the aldehyde 1 having the constitution andstereochemistry shown not only results in particularly positive scentcharacteristics but also that it is of particular industrial value owingto its behavior in perfume-technical applications. The compound 1 havingthe constitution shown and the analogous configuration has not yet beendescribed.

C-8-substituted tricyclo[5.2.1.0²,6 ]decane-derivatives without astatement relating to the stereochemistry at position C-8 are describedin U.S. Pat. No. 3,270,061 (Aug. 30, 1966). Among those is also the8-formyl compound D which, however, is not mentioned in the claims ofthe above mentioned patent. ##STR2##

In this description, the stereochemistry of the ring system is describedas 2,6-exo. However, this is not considered as being relevant for thescent characteristics of the mentioned or claimed compounds. In theabove mentioned patent in column 1, lines 69 to 72 there is a statementthat the compounds described usually and preferably consist of the2,6-exo-isomers and that the corresponding endo-isomers could, however,be used in the same way in accordance with the invention therein. Thereis also no statement about the possible importance of the C-8stereochemistry. It is therefore novel and surprising that the aldehyde1, meaning exclusively the 2,6 exo-configuration, with theexo-configuration of the formyl group at the C-8, provides a scent whichis characterised by a particularly natural and aesthetically valuablegreen note.

For the aldehyde D of the same constitution which has been obtained inaccordance with the U.S. Pat. No. 3,270,061 an intensive green notehaving earthy top-notes is mentioned (column 5, lines 69 to 71). In thispatent specification, it is also stated that the aldehyde D is of valuefor the formulation of heavy flowery notes, such as violet notes.However, in the U.S. patent, aldehyde D has not been claimed as a scent.In contrast, only ketones E which are produced by consecutive reactionshave been claimed and their scent characteristics have been extensivelydescribed. One can presume that owing to its earthy bynote aldehyde Dwas only of a limited value and hence has not found entry into theinternational perfumery.

The aldehyde D can be produced by analogy to U.S. Pat. No. 3,270,061from the tricyclic ketone A (TCD-ketone A, commercial product of thefirm Hoechst, Germany): by conversion with ethyl chloro-acetate in thepresence of sodium hydride the glycidic ester B is obtained; thesaponification of B results in the glycidic acid C which also could beconverted into the aldehyde D by heating with potassium acetate. Byreproducing the prescription given in U.S. Pat. No. 3,270,061 weobtained the aldehyde D at a purity of about 99% (Example 1). The knownscent characteristics could be confirmed by us. Surprisingly, we havenow found that under the effect of acids or bases, preferably ofalkaline hydroxides or alkaline carbonates in an alcoholic solution, aclear improvement of the scent of aldehyde D can be noticed. The scentof the treated material is not only clearly stronger, but also morenaturally green. ##STR3##

The analysis of the aldehyde D produced analogously to U.S. Pat. No.3,270,061 for the presence of other compounds after the treatment withacids or bases is difficult even using modern analytical methods. Thematerial produced in accordance with U.S. Pat. No. 3,270,061 (Example 1)was in our hands uniform when analysed by gas chromatography. After basetreatment (Example 3a), no peak separation can be observed even usinghighly effective quartz capillary columns; accordingly, the materialmust be unchanged. In order to clarify the olfactory differencesobserved for the aldehyde, which presumably was present as a mixture, weproduced the corresponding alcohol mixture in a known way by reductionwith lithium aluminum hydride. In this process other reducing agentssuch as sodium borohydride or even catalytic methods can be used.Surprisingly it has been found that by the reduction, an alcohol mixturehad been formed which could be separated by chromatography. This wasvisible, amongst other means, by clearly differing gas chromatographicretention times and significantly differing mass spectra. By separationusing distillation or chromatography, alcohols 3 and 4 have beenisolated and characterised spectroscopically.

By reduction of the stereo-isomeric aldehyde mixture to the alcoholmixture, its separation by physical methods followed by an oxidation,8-exo-formyl-2,6-exo-tricyclo[5.2.1.0²,6 ]decane (1) and its8-endo-formyl-isomers are obtainable in pure form. It was not possibleto directly separate the stereo-isomeric aldehyde 1/2 by chromatographyor by distillation. The stereo-isomerically pure aldehyde 1/2 can beequilibrated by the action of acids or bases, preferably by methanoliccaustic soda. The exo/endo-isomer ratio at the C-8 is 84:16 in anequilibrated mixture. The aldehyde mixture according to the U.S. Pat.No. 3,270,061 had a 58:40 ratio of the exo/endo isomer at the C-8, asdetermined by us by reduction of the alcohol mixture followed by thedetermination of the isomers using gas chromatography. Under equilibriumconditions we could also obtain from this isomeric mixture a producthaving an 8-exo/endo-ratio of 84:16. The effect of strong bases, inparticular of alkaline hydroxides in alcohol solutions, increases theC-8-exo/endo-ratio from 1.45:1 to 5.25:1. Therefore, this can be used toenrich the stereoisomer that is olfactorily preferred.

The glycidic ester synthesis with TCD-ketone A (A) can be in thepresence of antioxidants such as phenothiazine in pyridine withconcomitant use of sodium methylate (Example 3b). In a one-pot reactionthe saponification to the glycidic acid can be performed usingmethanolic caustic soda and the carboxylation resulting in theconversion of the aldehyde can be performed using acetic acid (that isin the presence of sodium acetate). ##STR4##

The performance of the reaction sequence as a one-pot reaction resultsin relatively low production costs. The pH-calibration during thedecarboxylation and the processing determines the ratio of isomers ofthe C-8-formyl-group (C-8-exo/endo=80:20). The raw-aldehyde mixtureproduced according to this process still contains a small residualamount of the starting material TCD-ketone A. The C-8-exo-enrichedaldehyde mixture 1/2 (80:20) can be isolated in a highly pure form viaits bisulphite adduct.

An alternative synthesis sequence starts with the2,6-exo-dicyclo-pentadiene (5) which can be converted into theunsaturated aldehyde mixture 6 by selective hydroformylation at the morereactive double bond at the norbornene part of the2,6-exo-dicyclo-pentadiene. The catalytic hydrogenation of 6 results inthe aldehyde mixture 1/2 of an C-8-exo/endo ratio of 4.3:1. Suchregion-selective hydroformylations are, for example, described in DE-A3447030. The catalytic hydrogenation of the unsaturated aldehyde mixture6 is preferably performed using palladium carbon under controlledreaction conditions. ##STR5##

A further alternative reaction path starts from the2,6-exo-tricyclo[5.2.1.0²,6 ]decene-8 (7), hydroformylation of whichdirectly results in the aldehyde mixture 1/2 which again can beconverted into the stereo-isomer mixture 1/2 with a high proportion of8-exo by equilibration. ##STR6##

The 8-exo-formyl-2,6-tricyclodecane (1) is distinguished from itsC-8-epimers 2 by especially advantageous scent characteristics. Theolfactory value of compound 1 also manifests itself in the mixtures ofthe diastereomers 1 and 2 if 1 is enriched, preferably to at least 70%compared to 30% of compound 2. The scent note of compound 1 can bedescribed as fresh-green and that of compound 2 as earthy, musty, green.Compound 1 not only is distinguished from the stereo-isomeric compound 2by a more advantageous note of scent, but also by a clearly largerstrength of scent. In perfume compositions, the olfactory value ofcompound 1 in a pure or in an enriched form (1/2=70:30) stands out evenat a relatively low dosage (see Examples 8, 9, 10). An enrichment of the8-exo-isomer 1 by even 10% when compared to the prior art led to a clearimprovement of the scent effect in the perfume arrangement according toExample 8. This clear and positive effect is reinforced by furtherenrichment of compound 1. The excellent stability and substantivity ofcompound 1 in a pure or in an enriched form and the positive scentcharacteristics described have the result that compound 1 in a pure orin an enriched form is a new and valuable scent.

EXAMPLE 1

Production of 8-exo/endo-formyl-2,6-exo-tricyclo [5.2.1.0²,6 ]decane (D=1/2) according to U.S. Pat. No. 3,270,061 a) column 4, lines 26-66; b)column 5, lines 19-65)

a) Production of glycidic esters B from ketone A

To a solution of 270 g (1.8 mol) TCD-ketone-A (A) and 245.2 g (2 mol)ethyl chloro-acetate in 900 ml of absolute toluene was mixed gradually60 g (2 mol) of 80% sodium hydride-dispersion in mineral oil over a 3 hperiod at 30° to 35° C. under stirring, whereby cooling with ice waterwas necessary owing to the exothermic reaction. After an additional hourof stirring at 30° to 35° C. the exothermic reaction ceased. Thereafter,the reaction mixture was stirred overnight without further cooling. Theexcess of sodium hydride was then neutralised by the careful addition of50 ml methanol. The reaction mixture was diluted with 500 ml water andrendered slightly acidic by the addition of 15 ml of glacial aceticacid. After removal of the organic phase the aqueous phase was extractedwith 150 ml toluene. The combined toluene phases were washed with aNaHCO₃ solution and water until they were neutral and then, the solventwas removed in a 20 mm vacuum. The remaining raw product (412.9 g) wasdistilled through a 20 cm Vigreux column. The yield was 302,6 g glycidicester B in the boiling range of 139°-145° C./1.5 mm. Gas chromatogram(30 m DBWAX, 100°-240° C., 6° C./min: t_(R) =15.3 (20.4%), 15.7 (29.5%),16.2 (20.3%), 16.9 min. (28.0%).

b) Production of aldehyde D via glycidic acid C

A solution of 118 g (0.5 mol) glycidic ester B in 275 ml methanol wasmixed under stirring over a 30 min period with a solution of 40 g NaOH(1 mol) in 350 ml H₂ O, whereby cold water cooling was necessary owingto the slightly exothermic reaction. Thereafter, the mixture was stirredfor 17 h without further cooling. Using a solution of 112 g conc. HCl in250 ml H₂ O the mixture was acidified to pH=3 and then extracted twicewith 150 ml toluene. The toluene extract was washed with water up topH=5.5 and then the solvent was removed in a 20 mm vacuum. 98.5 g rawglycidic acid C was obtained as a residue which was heated afteraddition of 3 g potassium acetate under vacuum. The product so formed isthen distilled through a 20 cm Vigreux-column. 71.5 g of aldehyde D (62%of the theory [th.] relative to the TCD-ketone-A (A)) in the boilingrange of 82°-87° C./1.5-2 mm were obtained as a colorless oil.

Gas chromatogram (30 m DBWAX, 100°-240° C., 6° C./min): t_(R) =13.0 min(98.6%).

Refractive index: n_(D) ²⁰ =1.5020 (Lit.:n_(D) ²⁰ =1.4999)

Density D₄ ²⁰ =1.0376

EXAMPLE 2

a) Reduction of the aldehyde mixture D (1/2) from Example 1

A solution of 8.2 g (50 mmol) of aldehyde D from Example 1 in 20 ml abs.diethyl ether was dropped into a suspension of 570 mg (15 mmol) LiAlH₄in 10 ml abs. diethyl ether at 0° C. under stirring and cooling.Thereafter, it was stirred over a period of 30 min at room temperature,and the surplus of LiAlH₄ was neutralised by the addition of 1 ml ethylacetate. It was then hydrolysed with 5 ml of ice water and the resultingsuspension was filtered over theorite. The filtrate was stripped of thesolvent in a 20 mm vacuum. 8.2 g of the alcohol mixture 3/4 was obtainedas a colorless oil.

Gas chromatogram (30 In DBWAX, 100°-240° C., 6° C./min):

t_(R) =17.8 (40% endo-isomer), 18.3 min (58%, exo-isomer)

b) Separation of the alcohol mixture 3/4

82 g of the alcohol mixture 3/4 having the composition mentioned aboveand being obtained by reduction of the corresponding amount of aldehydeD from Example 1 were subjected to fractional distillation at 110°-111°C. and to a 1 m spinning band column at 3.5 mbar. 37.9 g distillate wereobtained wherein the more volatile endo-isomer 4 was enriched to 80.6%.Additionally 40.8 g of distillate residue were obtained in which theexo-isomer 3 was enriched to 95.1%. By renewed distillation of thedistillate or a continued distillation of the distillation residue usinga 1 m spinning band column, the endo-isomer 4 and the exo-isomer 3 wereobtained in a purity of 98.3% and 99.6% respectively.

exo-isomer 3

IR (film): ν=3329, 2937, 1478, 1451, 1078, 1034, 994 cm⁻¹.

¹ H-NMR (300 MHz, CDCl₃): δ=0.8-1.05 (m, 4 H), 1.09-1.32 (m, 3H),1.51-1.67 (m, 2H), 1.72-1.90 (m, 4H), 1.94 ("s", 2H), 2.05 (br. s, 1H,OH), 3.33-3.43 ppm (m, 2H, CH₂ OH).

¹³ C-NMR (125.7 MHz, CDCl₃): δ=27.4 (t), 29.1 (t), 32.0 (t), 32.4 (t),33.1 (t), 40.6 (d), 42.4 (d), 44.4 (d), 47.8 (d), 48.5 (d), 66.5 ppm(t).

MS: m/z (%)=166 (0.4, M⁺) 148 (12), 135 (100), 107 (19), 93 (16), 91(16), 81 (13), 80 (18), 79 (37), 78 (11), 77 (14), 67 (47), 66 (10), 41(18), 39 (14), 31 (15).

endo-isomer 4

IR (film): ν=3316, 2958, 1475, 1452, 1070, 1056, 1035, 1014, 991 cm⁻¹.

¹ H-NMR (300 MHz, CDCl₃): δ=0.50-0.56 (m, 1H), 0.86-1.05 (m, 3H),1.07-1.25 (m, 1H), 1.40-1.46 (m, 1H), 1.58-1.74 (m, 3H), 1.77-1.94 (m,3H), 1.96-2.11 (m, 3H), 2.22 (br. s, 1H, OH), 3.48-3.60 (m, 2H, CH₂ OH).

¹³ C-NMR (125.7 MHz, CDCl₃): δ=27.1 (t), 32.2 (t), 32.7 (t), 32.8 (t),33.7 (t), 40.2 (d), 41.1 (d), 41.9 (d), 42.1 (d) 48.4 (d), 64.2 ppm (t).

MS: m/z (%)=166 (0.8, M⁺), 148 (25), 135 (85), 133 (31), 120 (45), 119(92), 107 (47), 106 (34), 105 (25), 95 (35), 94 (31), 93 (34), 91 (48),81 (34), 80 (52), 79 (100), 78 (20), 77 (30), 67 (72), 66 (23), 41 (28),39 (22), 31 (21).

EXAMPLE 3

Production of 8-exo/endo-formyl-2,6-exo-tricyclo [5.2.1.0²,6 ]decane(1/2) having an increased content of 8-exo-isomer 1 (starting from theTCD-ketone A)

Equilibration of the 8-exo/endo-aldehyde mixture D (1/2) from Example 1

5 g of the aldehyde D from Example 1 (exo/endo=58:40) was dissolved in amixture of 1 g 50% caustic soda and 25 g of methanol and was heated fora period of 30 min under reflux. After cooling the mixture was acidifiedwith 1 g glacial acetic acid and the methanol was removed bydistillation in a pre-vacuum. The residue was mixed with 25 g H₂ O andextracted with diethyl ether. The ether-containing extract wasneutralised by washing with a saturated NaHCO₃ solution and a 5%NaCl-solution, dried over Na₂ SO₄, and the solvent was removed in a 20mm vacuum. After bulb tube distillation of the residue (4.95 g) under a2 mm vacuum, 4.85 g of the product were obtained as a colorless oil.

refractive index: n_(D) ²⁰ =1.5021 density: D₄ ²⁰ =1.0365

After the reduction of an analytical sample using LiAlH₄ by analogy toExample 2 an exo/endo ratio of 84:16 was determined by gaschromatography.

Production of the aldehyde mixture 1/2 from TCD-ketone A (A) by modifiedglycidic ester synthesis

To a solution of 150 g (1 mol) TCD-ketone A (A), 165.4 g (1.35 mol)ethyl chloro-acetate and 0.5 g phenothiazine in 100 ml abs. pyridine wasadded gradually over a period of 1 hour 81 g (1.5 mol) of sodiummethylate by stirring and cooling at 15° C. After the addition of 74 gtertiary-butylmethyl ether the reaction mixture was stirred for afurther 4 h at 15° C. Then with cooling at 15° C. a solution of 125 g(1.56 mol) of 50% caustic soda in 297 g methanol was added, and it wasstirred overnight without further cooling. The mixture was acidifiedwith 468 g (3.9 mol) of 50% acetic acid and slowly heated to boil pointwhereby there was a strong initial development of CO₂. After 2 h underreflux 350 g of the solvent were removed by distillation through a 20 cmVigreux-column. The reaction mixture obtained was then diluted with 600g of 5% NaCl solution and extracted twice with 150 ml hexane. Thehexane-extract was neutralised by washing with NaHCO₃ solution and waterand the solvent was removed in a 20 mm vacuum. 155.2 g of the rawaldehyde were obtained which after a gas chromatogram still contained15% of the ketone A and which had an exo/endo ratio of 4:1 (asdetermined by gas chromatography after the reduction of an analyticalsample with LiAlH₄ in accordance with Example 2).

For the separation of ketone A from the aldehyde mixture 1/2 155 g ofthe raw aldehyde over a period of 30 min were dropped under stirringinto a solution of 104 g NaHSO₃ in 2 l H₂ O at room temperature. Thesuspension which was thereby formed was stirred for an additional hourat room temperature prior to two extractions with 150 ml hexane.Thereafter, the aqueous phase was rendered alkaline with 10% causticsoda and the resulting two-phase system was extracted twice with 250 mlhexane. The hexane extract was neutralised by washing with 5% NaClsolution and the solvent was removed in a 20 mm vacuum. The remainingraw product (117 g) was distilled through a 20 cm Vigreux column. 101.6g of the aldehyde mixture 1/2 (62% of the th.) in the boiling range of84°-86° C./1.5 mm were obtained as a colorless oil. GC-purity: 97.1%.

refractive index: n_(D) ²⁰ =1.5020 density: D₄ ²⁰ =1.0366

After the reduction of an analytical sample using LiAlH₄ an exo/endoratio of 80:20 was determined by gas chromatography.

EXAMPLE 4

Oxidation of the alcohol 3 from Example 2 (after separation of thealcohol 4)

A solution of 3.32 g (20 mmol) of alcohol 3 in 12 ml of abs. CH₂ Cl₂ wasadded to a well stirred suspension of 11.3 g (30 mmol) pyridiniumdichromate in 28 ml of abs. CH₂ Cl₂ in a nitrogen atmosphere at 0° C.and then stirring was continued for a period of 9 h without furthercooling. After dilution with 150 ml of diethyl ether the supernatant wasdecanted from the black residue, and the residue was washed three timeseach with 30 ml of diethyl ether. The combined organic solutions werefiltered over a silica gel, washed with 5% hydrochloric acid,neutralised by washing with NaHCO₃ solution and water. The solvent wasthen removed in a 20 mm vacuum. After bulb tube distillation of theremaining raw product (3.19 g) under a 2 mm-vacuum 2.87 g of aldehyde 1were obtained as a colorless oil.

GC-purity: 99.5%.

IR (film): ν=2704, 1719 cm⁻¹ (aldehyde).

¹ H-NMR (300 MHz, CDCl₃): δ=0.85-1.05 (m, 3H), 1.12-1.33 (m, 3H),1.61-1.69 (m, 1H), 1.81-1.97 (m, 5H), 2.04-2.09 (m, 1H), 2.22-2.28 (m,1H), 2.32 (br. "s", 1H), 9.66 ppm (d, J=1.5 Hz, 1H, CHO).

¹³ C-NMR (75 MHz, CDCl₃): δ=27.3 (t), 29.5 (t), 30.1 (t), 31.9 (t), 32.1(t), 40.4 (d), 42.2 (d), 48.10 (d), 48.13 (d), 54.3 (d), 203.2 ppm (d).

MS: m/z (%)=164 (4, M⁺), 135 (61), 108 (32), 107 (100), 106 (21), 93(27), 91 (20), 79 (58), 77 (20), 67 (88), 41 (28), 39 (21).

Oxidation of the alcohol 4 from Example 2 (after the separation ofalcohol 3)

Alcohol 4 was converted into the aldehyde 2 analogously as describedunder a). GC-purity: 98.1%.

IR (film): ν=2710, 1719 cm⁻¹ (aldehyde).

¹ H-NMR (300 MHz, CDCl₂): δ=0.85-1.04 (m, 2H), 1.07-1.22 (m, 2H),1.50-1.66 (m, 4H), 1.74-1.96 (m, 4H), 2.04-2.08 (m, 1H), 2.48-2.51 (m,1H), 2.65-2.72 (m, 1H), 9.79 ppm (d, J=1 Hz, 1H, CHO).

¹³ C-NMR (75 MHz, CDCl₃): δ=26.9 (t), 28.7 (t), 32.3 (t), 32.6 (t), 33.8(t), 41.7 (d), 42.7 (d), 43.0 (d), 48.1 (d), 53.3 (d), 205.0 ppm (d).

MS: m/z (%)=164 (3, M⁺), 120 (100), 118 (16), 107 (22), 92 (17), 91(31), 79 (44), 77 (16), 67 (28), 41 (20), 39 (16).

EXAMPLE 5

Production of 8-exo/endo-formyl-2,6-exo-tricyclo [5.2.1.0²,6 ]decane(1/2) from 8-formyl-2,6-exo-tricyclo [5.2.1.0²,6 ]decene-3(4) (6) byhydration

A solution of 370 g (2.28 mol) of aldehyde mixture 6 (obtained byregion-selective hydroformylation of 5) in 185 g of methanol were mixedwith 5 g Na₂ CO₃ and 1 g palladium on activated carbon (5% Pd) andstirred for a period of 4 h in a hydrogen atmosphere at 20 bar and45°-55° C. (use of H₂ : 102% of the theoretical). After filtration andconcentration, the hydrogenated mixture was dissolved in 100 g ofhexane, neutralised by washing with H₂ O and again concentrated. Theremaining raw product (375 g) was distilled through a 1 mVigreux-column. 327.4 g of the aldehyde mixture 1/2 were obtained (87.4%of the theoretical) in the boiling range of 84°-86° C./1.5 mm as acolorless oil. GC-purity: 98.5%.

After the reduction of an analytical sample using LiAlH₄ an exo/endoratio of 81:19 was determined by gas chromatography.

EXAMPLE 6

Production of 8-exo/endo-formyl-2,6-exo-tri-cyclo [5.2.1.0²,6 ]decane(1/2) from 2,6-exo-tricyclo[5.2.1.0²,6 ]decene-3 (7) by hydroformylation

A solution of 402 g (3 mol) of olefin 7 in 400 g of toluene was mixedwith a solution of 75 mg of dimeric rhodium(II)-2-ethyl-hexanoate in 20ml toluene and stirred under a synthesis gas atmosphere (mol ratio CO/H₂=1:1) for a period of 3 h at 100° C. and 180-200 bar (use of synthesisgas: 96.5% of the th.). After cooling to 30° C. the reaction mixture wasseparated from the solvent by distillation at 130 mbar and from thecatalyst at 2 mbar. The remaining raw product (486 g) was finelydistilled as described in Example 5. 440.8 g of the aldehyde mixture 1/2(89.6% of the theoretical) were obtained as a colorless oil. GC-purity:99.2%.

After reduction of an analytical probe using LiAlH₄ an exo/endo ratio of11:1 was determined with gas chromatography.

EXAMPLE 7

Determination of the strength of the scent of aldehyde mixtures 1/2

For the evaluation of the scent, solutions of the aldehyde mixture 1/2were prepared which contained the different isomeric ratios obtained bythe different processes. In each case the solvent was isopropylmyristate. In a series of dilutions a 1% solution of the test sample wasin each case further diluted with isopropyl myristate in a 1:10 ratio.

The test panel consisting of perfumiers determined the dilution at whicha scent could no longer be noticed. The concentration for the respectivethreshold value for the scent is marked by underlining.

Thereby it was found that the 8-exo-enriched aldehyde-mixtures 1/2 werestill noticeable, meaning they had a higher scent intensity, at a muchhigher dilution than the product produced by the known process (Example1).

    ______________________________________                                        1/2(58:40)                                                                             1/2(84:16)  1/2(81:19)  1/2(80:20)                                   according to                                                                           according to                                                                              according to                                                                              according to                                 Example 1                                                                              Example 3a  Example 5   Example 3b                                   1%       1%          1%          1%                                           0.1%     0.1%        0.1%        0.1%                                         0.01%    0.01%       0.01%       0.01%                                        0.001%   0.001%      0.001%      0.001%                                       0.0001%  0.0001%     0.0001%     0.0001%                                      0.00001% 0.00001%    0.00001%    0.00001%                                     0.000001%                                                                              0.000001%   .000001%    0.000001%                                    ______________________________________                                    

EXAMPLE 8

    ______________________________________                                        Perfume formulation                                                                          a        b      c                                              ______________________________________                                        Dihydro myrcenol 150        150    150                                        Patchouli oil, indonesian                                                                      100        100    100                                        Timberol*        100        100    100                                        Aldehyde D (according to                                                                       --          5     --                                         Example 1)                                                                    Formyltricyclo-decane 1/2                                                                      --         --      5                                         (according to Example 3a)                                                     Dipropylene glycol                                                                             645        645    645                                        ______________________________________                                         *DRAGOCO product                                                         

The mixture a is a perfume formulation having woody, flowery andsweet-herbal aspects. By the addition of 0.5% of aldehyde D (mixture b)the arrangement is more harmonic with concomitant emphasis on thegreen-flowery aspects. Through an alternative addition of 0.5%formyltricyclo-decane 1/2 (mixture c) an arrangement is obtained whichis stronger than (b) and which at the same time smells fresher flowery.

EXAMPLE 9

    ______________________________________                                        Perfume oil of the Chypre-type                                                                   a     b                                                    ______________________________________                                        oil of basil         1.5     1.5                                              oil of galbanum      4.5     4.5                                              dimethylbenzyl carbinyl acetate                                                                    7.5     7.5                                              Jasmine base*        30.0    30.0                                             mandarin oil         30.0    30.0                                             hexyl cinnamic aldehyde                                                                            45.0    45.0                                             Lignofix*            45.0    45.0                                             musk ketone          45.0    45.0                                             vetiveryl acetate    60.0    60.0                                             linalyl acetate      90.0    90.0                                             cis-3-hexenyl salicylate                                                                           90.0    90.0                                             phenylethyl alcohol  90.0    90.0                                             methyl ionone, gamma 75.0    75.0                                             benzyl salicylate    109.0   109.0                                            bergamot oil         120.0   120.0                                            Lyral**              150.0   150.0                                            formyltricyclo-decane 1/2                                                                          --      7.5                                              (according to Example 3a)                                                     ______________________________________                                         *DRAGOCO-product                                                              **IFFproduct                                                             

The mixture a has a well-balanced scent of the chypre-type havingaspects of agrumen. By addition of 0.75% of formyltricyclo-decane 1/2(mixture b) the scent impression shifts in a very desirable way into afresh-flowery direction with an emphasis of the underlying green-spicynote.

EXAMPLE 10

    ______________________________________                                        Perfume oil for detergents                                                                        a    b                                                    ______________________________________                                        Sandranol*             5      5                                               styrenyl acetate      10     10                                               aldehyde C14          10     10                                               Rose-oxide D* 10%     10     10                                               Cyclogalbanate*       15     15                                               Isodamascon* 1%       20     20                                               Buccoxime* 1%         20     20                                               citronellol           20     20                                               hexyl salicylate      20     20                                               Ketofix*              20     20                                               Veticol acetate*      25     25                                               geraniol              30     30                                               Lilial***             50     50                                               phenylethyl alcohol   50     50                                               Greenyl acetate*      50     50                                               benzyl acetate        60     60                                               Greenyl propionate*   60     60                                               Lignofix*             60     60                                               benzyl salicylate     70     70                                               methyl ionone, gamma  70     70                                               Galaxolide **, 50%    100    100                                              hexyl cinnamic aldehyde alpha                                                                       100    100                                              Lyral **              105    105                                              dipropylene glycol    15     15                                               formyltricyclo-decane 1/2                                                                           --      5                                               (according to Example 3a)                                                     ______________________________________                                         *DRAGOCO  product                                                             ** IFFproduct                                                                 ***Givaudanproduct                                                       

The mixture a shows a balanced sweet-flowery tone, which is well suitedfor adding perfume to detergents and fabric softeners. By addition of0.5% formyltricyclo-decane 1/2 mixture b is obtained having a "softer"scent impression. The flowery-caring impression in both cases is alsonoticeable on the washed textiles after one wash, whereby in the mixtureb the flowery-fresh note is emphasised.

We claim:
 1. 8-exo-Formyl-2,6-exo-tricyclo [5.2.1.0²,6 ]decane (1)##STR7##
 2. A process for the production of a scent product having afresh-green note and high stability, said process comprisingtransforming 8-exo/endo-formyl-2,6-exo-tricyclo[5.2.1.0²,6 ]decane(exo/endo ratio=1.45:1) into an aldehyde mixture having an increasedC-8-exo-ratio of at least exo/endo=5.25:1 using base catalysis.
 3. Aprocess for the production of a scent product having a fresh-green noteand high stability, wherein 2,6-exo-tricyclo-[5.2.1.0²,6 ]decene-8 ishydroformylated to 8-exo-formyl-2,6-exo-tricyclo-[5.2.1.0²,6 ]decane(1).
 4. A process for the production of a scent product having afresh-green note and high stability, wherein the process products inaccordance with claim 2, are reduced to the corresponding alcoholmixture from which the 8-exo-configuration methylol is isolated bychromatographic or distillation methods and wherein there is anoxidation to form pure 8-exo-formyl-2,6-exo-tricyclo-[5.2.1.0²,6]decane
 1. 5. The use of 8-exo-formyl-2,6-exo-tricyclo [5.2.1.0²,6]decane (1) as a scent or a component of scent mixtures.
 6. The use of8-exo-enriched mixtures of 8-exo/endo-formyl-2,6-exo-tricyclo[5.2.1.0²,6]decane having an exo-isomer proportion of at least 70% and anendo-isomer proportion of at most 30% used as scent-imparting agent oras a component of perfume oil compositions, for cosmetic and technicaluses.
 7. A process for producing a scent product having a fresh-greennote and high stability, said process comprising subjecting8-endo/exo-formyl-2,6-exo-tricyclo[5.2.1.0².6 ]decene-3 to catalytichydrogenation to form 8-endo/exo-formyl-2,6-exo-tricyclo-[5.2.1.0².6]decane.
 8. A process for the production of a scent product having afresh-green note and high stability, wherein the process products inaccordance with claim 7 are reduced to the corresponding alcohol mixturefrom which the 8-exo-configuration methylol is isolated bychromatographic or distillation methods and wherein there is anoxidation to 8-exo-formyl-2,6-exo-tricyclo- [5.2.1.0²,6 ]decane
 1. 9. Aprocess for the production of a scent product having a fresh-green noteand high stability, wherein the process products in accordance withclaim 3 are reduced to the corresponding alcohol mixture from which the8-exo-configuration methylol is isolated by chromatographic ordistillation methods and that there is an oxidation to pure8-exo-formyl-2,6-exo-tricyclo[5.2.1.0².6 ]decane
 1. 10. A process as inclaim 2, wherein said base catalysis is by means of an aqueousmethanolic solution of caustic soda at boiling temperature.
 11. Aprocess as in claim 7, wherein said catalyst is palladium carbon.
 12. Anaromatic composition comprising 8-exo-formyl-2,6-exo-tricyclo[5.2.1.0.².6 ]decane and 8-endo-formyl-2,6-exo-tricyclo [5.2.1.0.².6]decane, wherein the C8 exo:endo isomer ratio is at least 70:30.
 13. Anaromatic composition as in claim 12, wherein the C8 exo:endo isomerratio is at least 80:20.